This invention relates to a plane patch antenna having two conductive plates maintained in spaced-parallel relation to each other.
For example, Japanese Patent Kokai No. 59-200503 and 59-207705 disclose plane patch antennas having two metal disc plates maintained in spaced-parallel relation to each other by means of a plurality of metal pins. With such a prior art plane antenna, however, its usefulness is limited in land mobile radiotelephone applications, particularly where it is used in the rain. This is stemmed from the fact that the prior art plane patch antenna has an available frequency band width which is too narrow to absorb variations in its frequency characteristic which may occur in the rain.